docs: def vol(self, gain, type="amplitude", limiter_gain=None):
          """vol takes three parameters: gain, gain-type (amplitude, power or dB)
          and limiter gain."""
          self.command.append("vol")
          if type in ["amplitude", "power", "dB"]:
              self.command.append(type)
          else:
              raise ValueError("Type has to be dB, amplitude or power.")
          if limiter_gain is not None:
              self.command.append(str(limiter_gain))
          print(self.command)
          return self